4 ms·
The NCMEC hash list is private, and adversarial attacks require running gradient descent and being able to generate a hash value for arbitrary input.
by shuckles 5y ago
The NCMEC hash list is private, and adversarial attacks require running gradient descent and being able to generate a hash value for arbitrary input.
- josephcsible 5y agoAt least one of these two things must be true: either Apple is going to upload hashes of every image on your device to someone else's server, or the database of hashes will be available somehow to your device.
- josephcsible 5y agoTurns out there's a third option I wasn't thinking about: private set intersection. https://news.ycombinator.com/item?id=28097683 https://news.ycombinator.com/item?id=28097683
- shrimpx 5y agoIs it possible to narrow in on a hash using gradient descent? You can correlate distance between inputs to distance between hashes somehow?
- shrimpx 5y agoReplying to my own question since I can’t edit anymore: it turns out “perceptual hashing,” which I didn’t know much about, has exactly this property, that small changes in the input result in small changes in the output.